An individual organism whose body contains cell populations derived from different zygotes, of the same or different species, occurring spontaneously, as in twins or produced artifically, as an organism which develops from combined portions of different embryos, or one in which tissues or cells of another organism have been introduced.

chimera

T-cells and B-cells have a predisposed specificity to respond to a particular epitope or antigenic receptor. Each individual cell can respond to only __ epitope, but as a population either T- or B-cells have the capability to recognize approximately ___ different epitopes.

1, 1 billion

What is the immune repretoire (immune contingency)?

immune system has the potential to respond to perhaps 1 billion antigentic determinants.

Based on the genetics
constitution of the individual. These are nonspecific
means of clearing or removing most
undesirable substances

NON-SPECIFIC or INNATE IMMUNITY: (native
or inherent immunity)

(acquired
immunity) Specific immunity attributable to the
presence of antibody or reactive lymphocytes
following prior exposure to an infectious agent or
antigen.

SPECIFIC or ADAPTIVE IMMUNITY: (acquired
immunity)

PAMPs often initiate the non-specific immune response. What does PAMP stand for?

Pathogen-associated molecular patterns (PAMP)

What are some characterisics of PAMP? (4)

Characteristics:
• Produced only by microbial pathogens -- NOT HOST
• Usually essential for the survival or pathogenicity
of microorganism
• Usually invariant structures shared by entire
class of pathogens

A substance that can combine with Ab or be the target of cell-mediated immunity

Ag

___ is the property of a substance that allows it to react with products of specific immune response (Ab or specifically sensitized T-lymphocytes)

Antigenicity

A substance that when introduced into the body stimulates humoral or cell-mediated immunity

Immunogen

Defined as the property of a substance that endows it with the capacity to provoke a specific immune response

Immunogenicity

(A special class of Ag) A substance that can combine with Ab but can initiate an immune response only if it is bound to a carrier molecule. They often have low molecular weights (<1000) and only 1 or 2 antigenic determinants.

Hapten

T/F Substances that are antigenic are always immunogenic, but antigens are not necessary immunogenic.

False... substances that are immunogenic are always antigenic

Haptens can function as ___ but not ___.

Ag but not immunogens

Example of a hapten

PCN = penicillin

Determinants or region of antigenic substance which is recognized by Ab or cytotoxic T-cells

Epitope

T/F Ag may have many determinants or epitopes.

True

T/F Hapten is similiar to an Ab.

False, similiar to epitope

Group of antigens from apparently unrelated animals or microorganisms which are so closely related immunologically that they cross-react extensively with Ab against any one member of a particular heterophile group.

Heterophile Ag

Example of heterophile Ag

Forssman Ag is present on RBCs of many species as well as in some bacteria (pneumococcus and others)

-Secretory component (piece) is also called pIgR (polymeric immunoglobulin receptor).
-pIgR is a cell membrane receptor that binds to free dimeric IgA or pentameric IgM and transports them through endothelial cells before release at teh mucosal surface

4. One TCR is expressed, T-cells begin a process of interacting with various Class I or Class II MHC molecules expressed on thymic stromal cells

During step 5 of the T-Cell Maturation: Thymus processing of T-cells, describe the outcome and function of each interaction.
1. TCR does not bind to MHC molecule
2. TCR binds to both MHC molecule and peptide
3. TCR binds to MHC molecule but not peptide

T/F TCR recognizes the combination of the peptide and MHC molecule thus a particular T-cell will "work" both bussets of MHC molecule expressed by the individual.

False, will "work" with only one subset of individual.

Class I is expressed on virtually all __ cells and Class II is expressed on select __ __ cells.

-somatic
-Ag preseneting

T/F Some T-cells with auto-reactivity (recognize self peptides) will escape the thymus and must be made responsive by other means.

True

• Accelerated thymic involution is a hallmark of FIV infection of young cats and also pediatric AIDS. Why?

• The thymus is an early and major target
for FIV infection

Where do pre-T-cells originate from before reaching the thymus.

Bone marrow

T-cell will can express either __/__ or __/__ Ag receptors. If the T-cell has alpha/beta Ag receptors, it can then recognize the accessory molecules, __ or __. What will the varying functions be based up the accessory molecule.